I have an idea but I'm not sure if it makes sense or not.
I understand that CryptoNote uses addresses just twice, the first when a payment is received, and the next when a payment is made and that specific address is never used anymore.
Having that in mind, does it makes sense to think on a cryptocurrency with a limited number of blocks (let say one year of blocks), and if there are coins on an address that were not spend they are burned.
This way the disk usage of the full blockchain would be limited, and the usage of the coins would be enforced.
Does it makes sense? It is possible to implement something like that?